I have a friend who has fallen 50 feet into the sea from a helicopter while hoisting. That may sound like a pretty careless thing to do, but the fact of the matter is that for anybody whose job it is to descend on a wire cable from a helicopter in flight, it will always be an occupational hazard – if not the ultimate occupational hazard – associated with an activity that offers many others beside. Fortunately, not only did he survive to tell the tale, he is now back on the job, hanging out of helicopters.
When it’s done well, helicopter hoisting provides a supreme example of team dynamics, coordination and communication. Consequently, when things go wrong, whatever the circumstances, it is also a team responsibility. That’s the nature of a true team activity. I make this point first because when you consider what makes a helicopter crew successful in controlling and mitigating the multitude of potential hazards involved, it begins and ends with their ability to put their skills together as a team.
I wasted no time in gaining first-hand experience of this myself during piloting my very first live hoist rescue to a moving vessel. It was an episode that taught me a salutary lesson in just how fast things can go wrong. Early on a dark night off the south coast of the UK, we were tasked to a fishing vessel underway, with nobody apparently on board. On the way out to the vessel our searchlight failed, leaving us with only the struggling night vision goggles and a powerful hand-held spotlight to illuminate the deck. I was metaphorically to be dropped in the deep end! The vessel was completely unlit having been seemingly uncrewed for several hours and, when we arrived on scene, it was motoring away in a steady lazy right-hand turn. There weren’t many obvious choices for a transfer area, so having discussed our options, we decided that the most obstacle-free area to place the winchman was on the cabin roof, and we proceeded to attempt a dry run to assess references. The dummy transfer went remarkably smoothly, so without further delay we progressed with the live transfer. On this second run-in, I lost references on the turning vessel just as we came over the top, and rapidly drifted forwards, trawling the winchman, still attached to the hook, into a mast just forward of the cabin, tangling him and the hoist cable in the rigging. Luckily for me, he had the agility and the presence of mind to free himself and the hook before the situation became critical, and under the calm and controlled conning of the hoist operator, I was able to re-establish a hover.
What surprised me more than anything was that the whole sequence had happened in the blink of an eye. At the time, I could do little more than react to events and depend upon the trust I had in the abilities of the crew I was flying with. I have a citation in my logbook from the events of that night, mainly thanks to the efforts of other members of the crew. I am not particularly proud of the part that I played in it, but it did demonstrate to me the maxim that experience is something that you gain moments after you need it. The early lessons that I took from that flight have stayed with me ever since.
The anatomy of a winch cable
A 19x7 winch cable is made up of 19 bundles of seven strands of wound wire. Of these 19 bundles, seven are organized into an inner core, with another 12 bundles woven around the core binding the cable together. This arrangement makes it incredibly strong and resilient, owing to 133 separate strands of wire bound together to share the load. It can give a standard 3/16-inch diameter winch cable an ultimate static load of a remarkable 1,500kg. The anatomy of the winch cable and the way it offers a capability far beyond the sum of its parts provides an analogy for how we can successfully and safely work together as a crew when hoisting.
A winch cable model of hoisting competency
Just as the winch cable binds together its wire, the core elements of hoisting operations are made up of the interaction of seven strands of competency. These core competencies will look familiar to anyone in aviation and are made up of a mixture of technical and non-technical skills. The model (Fig 2) is shown, and the competencies are explained with examples of how we use them while hoisting.
A helicopter hoist operation cannot be an individual activity, so these competencies cannot function in isolation
A helicopter hoist operation cannot be an individual activity, so these competencies cannot function in isolation. As with the design of the cable, the seven core competencies are bound together by one encompassing competency: that of teamwork. Hoisting is the ultimate full crew flying task where team responsibilities – and even leadership – can move around fluidly between crew members during the mission. A crew depends upon each other’s knowledge, skills and abilities to achieve a goal and avoid the many hazards that the activity can expose. If you have the chance watch a well-trained crew hoisting, you will notice how the communication, division of workload, and awareness of the pilots, hoist operators, rescuers or other human external cargo fuse to create a single interdependent unit working together to complete a specific task.
Managing hoisting hazards
An open-source review of accidents from around the world in the last 10 years reveals there were 15 incidents while hoisting that led to fatal or severe injuries to crew members or casualties in the act of being rescued. Nine of these were falls. That’s an average of nearly one person a year being killed falling from the helicopter or the cable. The real numbers are likely to be higher. Other significant incidents included blade strikes, cable snagging, cable failure, dropped objects and aircraft emergencies while hoisting.
These are just the tip of the hoisting accident pyramid. The often-cited ‘Bird Triangle’ – named after safety researcher Frank E Bird’s analysis of 1.7 million industrial accidents – describes a ratio showing that beneath these 15 accidents that resulted in death or serious injury lie many thousands of other events of lesser gravity (Fig 3). Despite their less severe outcomes, it is here that we should be looking for the best opportunity to effectively control the risk associated with the activity.
In 2003, another study was conducted that suggested an even larger difference in the ratio of serious accidents and near misses. It found that for every fatality, there are at least 300,000 instances of risky behaviors – activities that are not consistent with training, standard operating procedures or safety procedures. That’s a lot of opportunities to identify and trap the smaller threats and ‘gotchas’ before they develop into more serious outcomes.
A crew depends upon each other’s knowledge, skills and abilities to achieve a goal and avoid the many hazards that the activity can expose
In helicopter hoisting, an awful lot can go wrong if you let it. Some examples that spring to mind can be found in Fig 4, although this is not an exhaustive list and I’m sure that there are plenty of others. Part of the human factors problem is that our brain can’t really be expected to assess, react to and address such a wide range of potential hazards in a consistent manner. We tend to latch on to what is salient to us based on past experiences, availability or training. Furthermore, the threat that we anticipate is unlikely to be the one that gets us!
I once carried out a case study in threat and error management where crews were told nothing more than the tasking details for a rescue flight requiring a hoist extraction. They were given information on such items as crew experience, weather, aircraft, equipment, and the nature and location of the task. I told them that the flight ended in an accident but left it to them to predict the cause based on what risks they perceived from the information given.
What I saw was a significant difference in predictions based on the individual’s role in the crew. The different experiences and perspectives of different crew members led them to identify and focus on different risks. They also judged the severity of those risks differently. For example, pilots imagined engine failures and botched flyaways, blade strikes, and loss of tail rotor control. Rear-crew predicted winch failures, falls and slips, and snagged cables. The lesson was that risk perception is a question of perspective, and therefore risk management requires multiple inputs from multiple perspectives.
Successfully mitigating risk when hoisting is a team collaboration from start to finish
Successfully mitigating risk when hoisting is a team collaboration from start to finish. It stands to reason that when evaluating a wide range of threats, one person’s perspective is inferior to multiple inputs from many different points of view. A model describing competent performance, such as this one, is just a framework, but it can assist in systematically identifying and working through potential hazards that a hoisting mission could present, as well as ways of considering barriers to effective team performance. Furthermore, most of this process can happen long before we reach the aircraft, because – as with any other high-risk activity – it is the culture, training and procedures that underpin crew behaviors where risk is most effectively managed, mitigated and controlled.